Human Diarrhea Parasite Found Lurking in Piglets

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An intestinal parasite that causes diarrhea in humans also makes
its home in pigs.

The existence of the single-celled parasite, Dientamoeba
fragilis, in pigs is important, the researchers explain,
because it might mean pig feces are one way the parasite
has been spreading to humans. More than a billion pigs are
housed in farms across the world.

In developed countries, D. fragilis infection rates in
people hover around 2 percent to 4 percent. But in developing
countries where
waste disposal is poor, infection rates of between 19 percent
and 69 percent have been reported. Travelers to these countries
also often fall prey to the parasite. Infection is sometimes
asymptomatic, but it can also cause diarrhea and abdominal pain.

Few animal hosts, or "reservoirs," for D. fragilis had
been discovered, researchers reported today (April 11) in the
journal Emerging Infectious Diseases published by the Centers for
Disease Control and Prevention. Pigs in Italy, however, were
reported as having
high infection rates. So Italian scientists collected and
analyzed 152 fecal samples from nine farms. They found that 52 of
74 piglets, 11 of 14 pigs at the "fattening" stage. and eight of
64 sows tested positive for D. fragilis. Young animals
appeared to be most susceptible.

Furthermore, the analysis showed that the parasite found in pigs
was the same one that infects humans. That means pigs could
transmit the parasite to humans, likely through their waste.

The researchers noted that the discovery could be a boon to
understanding D. fragilis. Little is known about the
parasite's life cycle, and pigs could provide a useful model for
understanding how transmission and infection occurs, the
researchers said.